Ive only had a dealer order from the factory once, and never will again which is another story, but only had to provide a $1000 deposit. That was on a selling price of a little less than $20K or about 5%.
That's a load of BS that the factory will not ship a unit until paid in full. Unless perhaps the dealer has shot his credit with the manufacturer all to helll by his own doing.
I had a real issue with the one sided wording on the paperwork though, that the deposit was non refundable. I crossed that out, wrote in my own terms, and had the GM acknowledge it in writing. A good thing too as the unit that arrived had major build issues and was not accepted.